Orthodontic braces comprised of a plurality of brackets and an arch wire for applying the appropriate force to a patient's teeth are commonly used to move the teeth into a desired configuration or alignment. Each bracket is firmly attached to its associated tooth and serves as a handle on the tooth for the force-producing arch wire. Early approaches provided control of the magnitude and direction of the orthodontic forces by incorporating appropriate bends in the arch wire. Later approaches employed a "straight wire", where the force vector directions were transferred from the arch wire to the individual brackets. This is accomplished by incorporating an arch wire-receiving slot in each bracket so that the desired force is applied to each tooth in the arch by simply attaching a straight length of wire having a rectangular cross section into the slot of each bracket. In a typical straight wire system, the bracket force vectors for specific tooth types are determined so as to match population averages. There is no individual adaptability for the specific needs of an individual patient. The patient's individual pretreatment malocclusion, dental morphology, and facial parameters do not enter into the specific treatment employed. If the bracket is not correctly positioned on the tooth, the desired displacement and/or reorientation of the tooth will not be realized.
Later approaches have employed orthodontic appliance placement methods which take into consideration the individual parameters of the patient. For example, U.S. Pat. No. 5,139,419 discloses a method of forming an orthodontic brace involving calculations based upon measurements of the patient's teeth for determining the positions, angles and depths of the arch wire-engaging grooves in the individual brackets of the appliance. A similar approach is disclosed in U.S. Pat. No. 5,395,238 which employs a mechanical probe of determining the contours of a patient's teeth. U.S. Pat. No. 5,011,405 discloses a method for determining orthodontic bracket placement involving the generation of digital information defining the shape and location of the maloccluded tooth in the patient's jaw, from which digital information a mathematical model of the tooth and jaw is generated for calculating the correct placement position of a bracket on the tooth. U.S. Pat. No. 4,551,096 discloses an apparatus and method for treating malocclusion involving the use of a fixture which fits over a tooth on which a bracket is to be affixed, where the shape and dimensions of the fixture match the shape and contour of a portion of the associated tooth. All of the aforementioned approaches employ a standard fixture, or jig, for positioning of the bracket on its associated tooth. The use of an off-the-shelf jig limits the accuracy with which the bracket can be positioned on the tooth as well as the precision with which the tooth can be aligned in the desired position and orientation.
The present invention addresses the aforementioned limitations of the prior art by providing a custom-shaped positioning jig for attaching an orthodontic appliance bracket to a tooth in installing orthodontic braces. The shape and configuration of the inventive positioning jig is determined using CAD/CAM techniques and the jig is provided with various features which facilitate its use, as well as its installation on and removal from a patient's teeth.